Contaminating substances accumulate in the environment as a result of solid and liquid landfills, industrial and agricultural activities. Many of these substances include chlorinated aromatics, stable molecules which affect various levels of the food chain. In particular, Pentachlorophenol (PCP), having being used extensively, has become a contaminant due to its toxicity and bioaccumulation. Several strategies to remediate polluted environments are based on physical and chemical methods or involve biological agents (Bioremediation). Bioremediation, as a spontaneous or controlled strategy, is considered a low-impact and sustainable methodology, compared to traditional clean-up techniques, and, consequently, ideal for recovering polluted ecosystems. Well-known bioremediation agents include plants and microorganisms, as well as their metabolites and enzymes. In contrast, animals such as insects, despite their remarkable versatility in developing resistance to xenobiotics, are much less exploited as a source of enzymes potentially useful in bioremediation programs. In order to fill this gap, we chose to study the effects of Pentachlorophenol (PCP) on Drosophila melanogaster. Potential metabolic pathways in D. melanogaster involved in detoxification of polyhalogenated aromatic hydrocarbons were investigated using a 90K Custom microarray. Microarray assays were performedon mRNA from early third instar larvae challenged with different PCP concentrations(0, 20 and 2000 ppm) incorporated in dietary supply. Linear Model for Microarray Data (LIMMA) analysis identified a set of 663 Differentially Expressed (DE) mRNAs among the control and the treated larvae (p≤0.05). The DE genes encoding enzymes potentially involved in detoxification included numerous cytochrome P450 genes (Cyp). In particular 8 Cyp genes were up-regulated (Cyp6a2, Cyp6a8, Cyp6a17, Cyp6d2, Cyp4d14, Cyp28d2, Cyp12a5, Cyp12e1) and 1 was downregulated (Cyp4d2). Overexpression was also detected in genes of the glutathione-mediated detoxification pathway: three glutathione-S-transferases (GSTD4, GSTD9, GSTS1), and a puromycin-sensitive aminopeptidase (alanyl aminopeptidase).
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